Copolymer of dimethallyl ether and an alkyl acrylate



Patented Jan. 30, 1951 COPOLYMER F DIMETHALLYL ETHERAND W AN ALKYL ACRYLATE Robert H. Snyder, Chicago, Ill., assignor to United States Rubber Company, New York, N. Y., a corporation of New Jersey N 0 Drawing. Application April 19, 1946,

Serial No. 663,618 r 3 Claims.

My invention relates to the preparation of soluble, convertible resins from dimethallyl ether and an ester of an acid from the class consisting of propenoic acid and 2-alkyl propenoic acids with a non-enic monohydric alcohol, here inafter designated a propenoic ester.v

As shown in U. S. Patent No. 2,160,943, the copolymerization of a ternary mixture of an acrylic ester and vinylidene chloride with small "amounts of dimethallyl ether results in the formation of infusible and/or insoluble products. Such materials are difficult to manipulate in subsequent processing and are of limited utility in many commercial applications such as coating, impregnating and laminating operations wherein soluble, fusible resins, capable of being ternary interpolymers of a propenoic ester} vinylidene chloride and dimethallyl ether, I have now unexpectedly found that a propenoic ester in the absence of other polymerizable compounds can be copolymerized directly with dimethallyl ether to give excellent yields of soluble, unsaturated resins. Further, I have made the sur-- prising discovery that as the molar ratio of the cross-linking dimethallyl ether to the propenoic ester is increased above approximately 1:5, the amount of the propenoic ester which can be converted to the polymeric form before gelation, is also increased, and in the presence of a sufficient quantity, e. g., a molar ratio of 4:1, of the dimethallyl ether,'essentially all of the propenoic ester can be converted to unsaturated copolymer without insolubilization. Moreover, it is also possible by my invention to secure soluble copolymers which, unlike those of the prior art, can contain considerable amounts of the dimethallyl ether. prepare a soluble copolymer of methyl acrylate and dimethallyl ether in which the ether constitutes over 50% by weight of the product.

' In further contrast to the prior art, the products obtained according to my invention show flittle'or no tendency to cure to the insoluble, infusible state even when heated at elevated temperatures, e. g., 100 C., with peroxidiccatalysts; a though they gradually become insoluble and even infusible upon prolonged heating at For example, I can readily- Icon solvents.

. v 2 y ing to my invention behave for many purposes as soluble thermoplastic resins and are useful as such. In view of the resistance of these unsaturated copolymers to further polymerization, it is surprising to find that they copolymerize readily with reactive monomers containing an ethylenic linkage C=C e. g., diethyl fumarate, to yield insoluble, infusible products. This property extends the utility of my copolymers to include not only the thermoplastic but the thermosetting types of resins as well.

Copolymers prepared according to my invention range in character from easily comminuted solids to viscous or plastic masses depending upon the relative proportion of the reactants and upon the choice of an appropriate propenoic ester. In general, the softening points and molecular weights of the copolymers tend to decrease as the amount of the dimethallyl ether in the reactant mixture is increased. For any given molar ratio'of dimethallyl ether to propenoic ester, copolymers derived from the propenoic esters of lower alcohols, e. g., methanol and ethanol, will be harder and higher melting, while the propenoic esters of. the higher alcohols, such as n-butanol and octyl alcohol, yield copolymers of the softer, more plastic type which likewise possess a greater compatibility with hydrocar- Suitable propenoic esters for use in my invention are represented by the type formula CH2=C(R)CO-OR where R is one of the radicals, hydrogen and alkyl, e. g., methyl and ethyl, and R. is one of the radicals, alkyl, e. g., methyl, ethyl, propyl, isopropyl, butyl, etc.; aryl, e. g., phenyl; and aralkyl, e. g., benzyl.

Exemplary of such esters are n-butyl acrylate,

methyl methacrylate, methyl acrylate, methyl ethacrylate, and phenyl acrylate, etc. Products of physically intermediate character can be secured by copolymerizing dimethallyl ether with a mixture of propenoic esters, such as methyl methacrylate and butyl acrylate; or by an alcohol interchange between the binary copolymer and the appropriate alcohol, e. g., between the methyl ester copolymer and butanol, hexanol,

by distilling off any unreacted starting materials or by extracting them with a solvent, e. ,g., aqueous methanol, in which the copolymer :is insoluble. Although unnecessary in most commercial applications my copolymers can be further purified for specialized uses by solution in a solvent, such as acetone and iprecipitation' with a non-solvent, such as a methanolwater znixture.

freed from solventsgm y 'copolym'ers can be cast or molded a known manner to form rodsgblocks-sheets, e arid iii-this form they are particularly useful where clear, ilexihle articies are required such as safety glass interlayers. Alternatively; the copolymers ean foe dissolved in theisolvents and used'for'coati'ng and impregnafionqarocesse's. theipreparation of such solutions I it is "often unnecessary "to -iso'late the copolymen'for higher-boiling solvents, e. g, xy-lene'can be added directlytothecrudecopolymerizationreaction mixture and unreacte'd starting'materia' ls can then-*be retrnove'd by fractional distillation. Suitable dyes, pigments, fillers, plasticizers, and-resins can "be incorporated with my copolymers to 'm odify the character "for specific applications.

"Where heat and'solveiit-resistant materials are desiredgmyproduc'ts'cari beeasiiy converted to the insoluble, infusible state by copolymerization with reactive compounds containing an ethylenic dinkagesilchas methylacifylatejdiethylfumarate, -diallyl furnarate, et'c. copolymers dissolve readily in -a number or" these reactive ethylenic compounds 'to form "solutions, m-any of which display low viscosities even-at reiativelyhig-h sclids content. These solutions eahhetotaHy-polymerized leaving no'solvent to beevaporated; and this property renders :them. particularly suitable for coating and impregnating compositions, which can be'cured to-the insoluble,'infusible state with amnimu-m of abloviing,'shrinking'and distortion. Curing temperaturesfrom-:-C.:-to

420 C. are suitable.

The 'following examples illustrate -my-invention, in more detaiL-parts'being byweight:

EXAMPLE 1 mercial-gradeof n-hexane. Theprecipitatedcopolymers are-further purified :bymepeated-solutien inchloroiormand-precipitation'with n-hexano -After drying in vacuo-toconstant weight, the amounts of the-copolymericproducts areQdetermined.

' zation.

The pertinent details are summarized in Table I, including the Weights of the copolymerizable monomers, the peroxide catalyst and the copolymeric products as well as the reaction times. For purposes of comparison only, the polymerization of dimetha llyl ether inthe absence of an acrylic ester is also included (If) to show that dimethallyl ether polymerizes with itself only to a negligible extent. in

Table I Methyl Dim'ethcllyl Benzoyl Polmeric Acrylatc Ether Peroxide g Product 100 36. 6 O. 03 l. 00 23. 3 100 146. 0 0. l2 2. 33 48. 4 100 220. 0 3. 49 2. 00 74.6 100 342. 0 4. 10. 00 89. 3 585. O 6. 97 165.0 162.0 f 100 0. 823 450. 0 2. 3

that the amount of soluble copolymer obtained prior .to :gela-tion increases with the amount'loi dimeth-allyl ether present in the reaction mi x ture. allyl ether :alonepossesses only :a 7 small tendency to homopoly-merize, the increasing amounts of copolymers correspond to conversions of increas ing amounts of the acrylic ester, :as-wel1--as t1;ie dimethallyl ether, to the copolymeric form.

EXAMPLE "2 -(a) A mixture of 6&8 parts of methyl-acrylate, 353:8;parts of dimeth-allyl ether. andz parrts oiga 60% solution of tertiary-butyl hydrogen gperoxide is heated at 90-C. f-or 24 hours, afterwhich the mixture is cooled to-.-25- Csand a trace of-hy- :droquinone added testabilize the mixture "for storage during subsequent processing operations. (b) One hundred parts-Ofthecrude reaction :mixture .from (a) areevacuated at 20 mm. pressure arid the residual rsyr-upais poured into n-hexane which'precipitates the-polymeric products. Further purification is effected b repeated solution of @the copolymer in :chloroform and precipitationwith n-hexane and-aiter-diydug in vacuo to constant weight v244)upartspof polymeric solid are :obta-ined which corresponds tcv-a total yieldoi 1101.5 parts frorn'the'entirereaction mixture. The-copolymer is readily soluble in acetone, chloroform, benzene and xylene. Upon heating, it begins to ilow sit-approximately 158 C. and-slowly becomes converted-to an in!- soluble, infusible-state at 185 C.-l90-C.

Analysis Found: C, 66.25%; 9.30% :iodin (WiJ'S) number *842; limiting viscosity E1 10 in acetone, 0:143. a

The analysis corresponds to a -copolymeracon taining approximately 49.0% by =xveight.0f-.methyl aerylate, and 251.0% of 'rdimetha-llyl ether: iodine number indicates th "presence 10f unsaturation which .is--availab1e for furtherrpolymeri- (0) One-hundred parts --cf--the--crude reaction mixture from (11) are-admixed with -10.3-,parts.of -diethyl fumarate and: evacuated at 40--C.=;and 5 mm.;pressure tou-a -viscous :syrup. One and four-tenths *partsrof benzoyl peroxide mare their addedpand the resin solution" is .cured.in-a.-.cylin- .drical mold-:by (heating: for 13 -.l1oursw at 50 10., 152 =hours at-90--.C.,-and'finally mp2 hoursat .C- .Theeresultant casting is clear; 11 ardand-insial1ible in chloroform. A

The contents of Table I clearly demonstrate Since --exam ple .I shows that dimeth EXAMPLE 3 (a) Seveny-six and nine-tenths parts of nbutyl acrylate are admixed with 265.1 parts of dimethallyl ether and 2.1 parts of a 60% solution of tertiary-butyl hydrogen peroxide, and heated at 130 C. for 24 hours after which the reaction mixture is cooled to room temperature.

(5) One hundred and fifty parts of the crude reaction mixture were purified as in Example 2b above, using 80% aqueous methanol as a precipitant in place of n-hexane, to yield 59 parts of plastic solid which corresponds to a total yield of 134 parts of copolymer from the entire reaction mixture.

Analysis Found: C, 69.92%; H, 10.10%; iodine number 70.1; [1 10 in acetone, 0.073.

The analysis indicates a copolymer comprising approximately 58.7% by weight of n-butyl acrylate and 41.3% of dimethallyl ether.

EXAMPLE 4 A mixture of 38.5 parts of isobutyl acrylate, 132.6 parts of dimethallyl ether and 1.05 parts of tertiary-butyl hydrogen peroxide solution is heated at 130 C. for 24 hours. Purification of a sample of the reaction mixture indicates a total yield of 75.5 parts of coplymer.

Analysis Found: C, 70.74%; H, 10.40%; iodine number 65.8; [1 10 in actone, 0.064.

The analysis corresponds to a copolymer containing approximately 49.2% by weight of isobutyl acrylate and 50.8% of dimethallyl ether.

Seven parts of the copolymer are dissolved in 3.0 parts of diethyl fumarate together with 0.4 part of benzoyl peroxide and heated in a mold at 60 C. for 15.5 hours and then for 2 hours at 120 C. The resulting clear casting is insoluble in acetone.

While I have shown and described various embodiments of the invention, it is to be understood that the invention is susceptible to those modifications which appear within the spirit of the invention and the scope of the appended claims.

Having thus described my invention, what I claim and desire to protect by Letters Patent is:

1. A method which comprises polymerizing with heat in the presence of a peroxidic polymer- 6. ization catalyst a mixture of monomers containing as the sole polymerizable components dimethallyl ether and material from the class consisting of esters of acrylic, methacrylic and ethacrylic acids and in which the ester radical is a saturated hydrocarbon radical having from 1' to 8 carbon atoms, at a temperature in the range from about 25 C. up to the reflux temperature of the mixture, to form a soluble unsaturated interpolymer of said monomers, in which the molar ratio of the ether to the ester ranges from 1 :5 to 4:1.

2. A method which comprises polymerizing with heat in the presence of a peroxidic polymerization catalyst a binary mixture of monomers containin as the sole polymerizable components, dimethallyl ether and an ester of acrylic acid in which the ester radical is a saturated hydrocarbon having from 1 to 8 carbon atoms, at a temperature in the range from about 25 C. up to the reflux temperature of the mixture, to form a soluble unsaturated copolymer of said monomers, in which the molar ratio of the ether to the ester ranges from 1:5 to 4:1.

3. A soluble binary copolymer of monomeric dimethallyl ether and an ester from the class consisting of alkyl esters of acrylic, methacrylic and ethacrylic acids and in which the ester radical is a saturated hydrocarbon radical having from 1 to 8 carbon atoms resulting from a binary monomeric mixture in which the molar ratio of the ether to the ester ranges from 1:5 to 4:1.

ROBERT I-I. SNYDER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,100,900 Fikentscher et al. Nov. 30, 1937 2,332,895 DAlelio Oct. 26, 1943 2,340,111 DAlelio Jan. 25, 1944 2,492,169 Mast et al Dec. 27, 1949 OTHER REFERENCES Norrish et al., Proc. Royal Society, vol. 163A (1937), pp. 205-220.

Powers, Synthetic Resins and Rubbers, J. Wiley and Sons, Inc., New York, page 146. 

1. A METHOD WHICH COMPRISES POLYMERIZING WITH HEAT IN THE PRESENCE OF A PEROXIDIC POLYMERIZATION CATALYST A MIXTURE OF MONOMERS CONTAINING AS THE SOLE POLYMERIZABLE COMPONENTS DIMETHALLYL ETHER AND MATERIAL FROM THE CLASS CONSISTING OF ESTERS OF ACRYLIC, METHACRYLIC AND ETHACRYLIC ACIDS AND IN WHICH THE ESTER RADICAL IS A SATURATED HYDROCARBON RADICAL HAVING FROM 1 TO 8 CARBON ATOMS, AT A TEMPERATURE IN THE RANGE FROM ABOUT 25* C. UP TO THE REFLUX TEMPERATURE OF THE MIXTURE, TO FORM A SOLUBLE UNSATURATED INTERPOLYMER OF SAID MONOMERS, IN WHICH THE MOLAR RATIO OF THE ETHER TO THE ESTER RANGES FROM 1:5 TO 4:1. 